class Point {
     int x,y;
     void setXY(int m,int n) {
       x = m;
       y = n;
     }
}
public class Example4_4 {
    public static void main(String args[]) {
       Point p1,p2;
       p1 = new Point();
       p2 = new Point();
       System.out.println("p1的引用:"+p1);
       System.out.println("p2的引用:"+p2);
       p1.setXY(1111,2222);
       p2.setXY(-100,-200);
       System.out.println("p1的x,y坐标:"+p1.x+","+p1.y);
       System.out.println("p2的x,y坐标:"+p2.x+","+p2.y);
       p1 = p2;
       System.out.println("将p2的引用赋给p1后:");
       System.out.println("p1的引用:"+p1);
       System.out.println("p2的引用:"+p2);
       System.out.println("p1的x,y坐标:"+p1.x+","+p1.y);
       System.out.println("p2的x,y坐标:"+p2.x+","+p2.y);
     }
}
